In recent years, a lithium ion battery, etc. is widely used as a secondary battery. High-energy density and high durability are required for a secondary battery, depending on the field of application. For example, a lithium ion battery comprises an electrode assembly (electrode group) in which a lamination of a cathode and an anode is wound with a separator being interposed therebetween. The lithium ion secondary battery comprises a configuration in which an electrode assembly is sealed in a battery can (outer can) filled with an organic electrolyte.
To increase the capacity of the secondary battery, it is important to secure a maximum space for the electrode group. To make the secondary battery capable of high-power, it is important to secure a maximum cross-section area of conductive paths, such as leads, etc., and to inhibit heat generation by reducing the resistance of conductive paths. Thus, the configuration for increasing the capacity of the secondary battery and the configuration for making the secondary battery capable of high-power is a tradeoff between a maximum space for the electrode group and a largest cross-section area of conductive paths.
A common method of assembling a secondary battery is a method by which terminals and leads, etc. are first fixed to the caps, and then the caps to which the terminal and leads, etc. are fixed are connected to the electrode group, and there are constraints on the assembly process, as well as the aforementioned tradeoff.
To solve the problem, a secondary battery and a method of manufacturing a second battery that allows an increase in capacity to be compatible with a high-power battery are provided.